The present invention relates generally to the interfacing with computer devices by a user, and more particularly to devices used to provide input to computer systems and which provide force feedback to the user.
Humans interface with electronic devices in a variety of applications, and there is a constant need for a more natural, easy-to-use, and versatile interface device. One of those applications includes interacting directly with computer-generated environments. Interface devices are used extensively with computer systems in the implementation of computer-controlled games, simulations, and other applications very popular with the mass market of home consumers. In a typical implementation, a computer system such as a personal computer, home video game console, portable computer, stand-up arcade machine, etc., displays a graphical environment to a user on a display device. Users can interact with the displayed environment by inputting commands or data from the interface device. Popular interface devices include joysticks, “gamepad” button controllers, mice, trackballs, styluses, tablets, steering wheels, pressure spheres, foot or hand pedals, or the like, that are connected to the computer system controlling the displayed environment. The computer updates the environment in response to input signals from the interface device based on the user's manipulation of a moved manipulandum such as a joystick handle, wheel, or mouse. The computer provides visual feedback to the user using the display screen.
In some interface devices, tactile and/or kinesthetic feedback is also provided to the user, more generally known as “haptic feedback” herein. These types of interface devices can provide physical sensations to the user manipulating the physical object of the interface device. Typically, motors or other actuators of the interface device are coupled to the manipulandum and are connected to the controlling computer system. The computer system receives sensor signals from the interface device and sends appropriate force feedback control signals to the actuators in conjunction with host events. The actuators then provide forces on the manipulandum. The computer system can thus convey physical sensations to the user in conjunction with other visual and auditory feedback as the user is contacting the manipulandum. Commercially available force feedback devices include the Wingman Force joystick and Wingman Formula Force steering wheel from Logitech, Inc., and the Sidewinder Force Feedback Pro joystick from Microsoft Corporation.
Many types of actuators for generating computer-controlled forces are known, including DC and stepper motors, voice coils, hydraulic actuators, and pneumatic actuators. Some devices are active, such as motors, which means that the device provides an active force that has the ability to move an object or push back on the user. Other actuators are passive, such as brakes, which provide a resistance to motion generated by another source (such as the user) and cannot generate forces on their own. An advantage of active devices is their ability to simulate all kinds of force sensations. However, disadvantages of active actuators include instability: the actuators can settle into a feedback loop in which oscillating forces are output on the manipulandum, for example. Other disadvantages of active actuators include a high cost, and large size and weight. Passive actuators, on the other hand, while not able to output all the types of force sensations of active actuators, can provide relatively high magnitude forces and are inherently stable and safe, and are typically of low cost and weight. However, standard passive actuators can still be expensive for lower-cost devices and can still add significant weight to an interface device.